LAFAYETTE — In what is being hailed as the largest such bust in U.S. history, federal officials announced Wednesday the arrests of 52 people involved in an international online child exploitation ring that will be prosecuted out of Shreveport.

Operation Delego targeted those who participated in Dreamboard, a members-only, online bulletin board created and operated to promote pedophilia, according to a news release.

The ongoing investigation was launched in December 2009 and to date has targeted 72 charged defendants and more than 500 additional people from around the world for their participation in Dreamboard, the news release said.

“The members of this criminal network shared a demented dream to create the pre-eminent online community for the promotion of child sexual exploitation but for the children they victimized, this was nothing short of a nightmare,” U.S. Attorney General Eric Holder said in a statement Wednesday.

The lead prosecutor in the case is Assistant U.S. Attorney John “Luke” Walker, Project Safe Childhood coordinator for the Western District of Louisiana. Walker handles child exploitation cases for the Western District.

Walker said the case is based in Shreveport because of Edward Oedewaldt, of Arcadia, an alleged member of Dreamboard who used the screen names “twelvish” and “Legend” while on the board.

Oedewaldt was the first member of the board to be identified, Walker said.

Walker said Oedewaldt “was a significant member of the board” although he could not say how significant as it was not yet public record.

Oedewaldt is the only known defendant from Louisiana, officials said.

Walker, who works out of the Western District’s Lafayette office, called it “an incredibly far-reaching case with “many, many victims.”

“I couldn’t even begin to guess the numbers. Both here and abroad, it’s staggering,” he said.

Dreamboard members traded graphic images and videos of adults molesting children 12 years old and under, often violently, and collectively created a massive private library of images of child sexual abuse, the release said.

The international group prized and encouraged the creation of new images and videos of child sexual abuse — numerous Dreamboard members sexually abused children, produced images and videos of the abuse, and shared the images and videos with other members of Dreamboard, according to the release.

Dreamboard members employed a variety of measures including computer encryption programs, which were designed to conceal their criminal activity from detection by law enforcement, officials said.

Membership was tightly controlled by the administrators of the bulletin board, who required prospective members to upload child pornography portraying children 12 years of age or younger when applying for membership, the release said.

Once they were given access, members were required continually to upload images of child sexual abuse in order to maintain membership. Members who failed to follow this rule would be expelled from the group, the release said.

Members, who used screen names like “clubkidsforever,” “Perversser” and “Slipnslide,” were divided into groups based on their status and ranking, which determined how much content a user could access.

Those at the highest level, referred to as “Super VIP,” created their own images of child pornography by molesting children and sharing those images with board administrators, the release said.

Among the rules of Dreamboard:

“Keep the girls under 13, in fact, I really need to see 12 or younger to know your (sic) a brother,” according to a superseding indictment in the case.

All 72 of the defendants are charged with conspiring to advertise and distribute child pornography, and 50 of them are also charged with engaging in child pornography enterprise.

The charges and arrests were conducted in three separate phases over the course of the operation.

To date, 13 of the 52 defendants have pleaded guilty, while 20 of the 72 remain at large and are known only by their online identities.

Four of the 13 people who pleaded guilty have been sentenced to prison, receiving sentences ranging from 20 to 30 years in prison.

The investigation involved international cooperation and has led to the arrests of 19 Dreamboard members across five continents and 13 countries, including Canada, Denmark, Ecuador, France, Germany, Serbia and Sweden.

Officials have confirmed that 15 arrested members personally created child pornography, the release said.

Operation Delego began as a spin-off investigation from leads developed during the prosecution of another online group dedicated to the sharing and dissemination of child pornography, the release said.

Stephanie Finley, U.S. attorney for the Western District of Louisiana, said in a statement that she hopes “these charges send a clear message that we will prosecute to the fullest extent of the law those who participate in this type of activity.”